Fuse valve



P. L. REYNOLDS March 2, 1954 FUSE VALVE 2 sheets-sheet 1 Filed April 1l, 1949 Null Patented Mar. 2, 1954 FUSE VALVE Philip L. Reynolds, Jackson, Mich., assigner, by mesne assignments, to Howard Field, Jr., Los

Angeles, Calif.

Application April 11, 1949, Serial No. 86,786

(Cl. IS7-87) 1& Claims. 1

My invention relates in general to valves and, more particularly, to valves which permit passage of uid through fluid lines connected thereto only if such fluid lines are intact, valves of this character commonly being referred to as fuse valves. A primary object of the invention is to provide an improved valve of this type.

The invention is of particular utility in aircraft hydraulic systems and will be considered in connection with such a system for purposes of illustration. However, it Will be understood that the invention is susceptible of application to" other installations and that I do" not intend to be limited to the particular illustrative application elected for consideration herein.

An aircraft hydraulic system normally includes one or more double-acting hydraulic units for each movable component Which is to be hydraulically actuated. For example, such movable components of an airplane as its landing gear, ilaps, control surfaces and the like may be hydraulically actuated. Each hydraulic unit comprises a cylinder having a piston therein which isl mechanically connected to the component to be actuated, and is controlled by a four-way selector valve which is connected to the ends of the cylinder by fluid lines.. Such a hydraulic system also includes a pump and a reservoir connected to the inlet of the pump, the selector valve being connected to the outlet of the pump and to the reservoir by additional fluid lines.` As is well known in the art, the selector value may be moved from an inoperative or closed position, wherein no uid dow occurs, to either one of a pair of operative or open positions, one end of the hydraulic cylinder being connected to the pump and the other end to the reservoir when the selector valve is in one of its operative positions, and the connections' being reversed when the selector valve is in its other operativev position.

If, in such a hydraulic system, one of the fluid lines connected to the hydraulic unit breaks for any reason, all of the fluid may bleed fromv the system toV render it inoperative. Such fluid line breakage may result from vibrational stresses,` or, in the case of military aircraft, from enemy action.

In order to prevent excessive loss of fluid from the system in the event of line breakage, fuse valves are usually inserted in the fluid lines lead'- ing to one or more hydraulic units, such valves being adapted to interrupt fluid iioW inthe event of breakage of the uid lines connected thereto. Ordinarily, such fuse valves are located as close as possibley to the pump and reservoir to minimize the length of the unprotected fluid lines.- An example of a prior fuse valve employed for this purpose may be found in the application of Robert B. Sprague and Searle G. Nevius, Serial No. 478,102, led March 5, 1943, now Patent Number 2,478,210, an object of the present invention being to provide a fuse valve which is an improvement on that disclosed in the aforementioned application.

Another object of the invention is to provide a fuse valve which includes displacement and metering means for sending a sample or test stream of uid through the lines connected to the hydraulic unit associated with the valve to determine whether the lines connecting the unit and the valve are intact. More specifically, an object of the invention is to provide a fuse valve which includes means for metering iiuidinto the pressure line leading to the hydraulic unit, and which includes displacement meansr for introducing additional fluid into such pressure line from an accumulator.

Another object is to provide a fuse valve having means for terminating the test stream after a predetermined quantity of fluid has been introduced into the pressure line' leading to the hydraulicv unit.

An important object of the present invention is to provide a fuse valve capable of introducing into the pressure line leading tothe hydraulic unit a sample of fluid which is substantial-ly independent of the viscosity of the fluid employed, and which is, therefore, substantially independent of temperatu-re. In other words, an object of my invention is to provide a fuse valvewhich will introduce into the pressure line substantially the same quantity of test fluid in extremelyl cold and in extremehr hot climates.

Another object is to provide a fuse valve Wherei-n the volume of the accumulator is small compared to the sample of uid.

A further object is to provide a fuse valve having a main or primary valve which may be opened either manually, or in response to a return flow of uid from the hydraulic unit to f' which the fuse valve is connected.

An important object of the invention is to provide a fuse valve wherein the main or primary valve is hydraulically actuated to minimize the forces required for manual operation thereof.

Another object is to provide a fuse valve having a minimum number of parts and one which may be manufactured and serviced readily.

The foregoing objects and advantages of the present invention, together with various other objects and advantages which will become apparent, may be attained through the employment of the exemplary embodiment iilustrated in the accompanying drawings and described in detaii hereinafter. Referring to the drawings:

Fig. 1 is a diagrammatic view of a hydraulic system incorporating a fuse valve which embodies the invention;

Fig. 2 is a sectional view of the fuse valve of the invention and is taken along the broken line 2--2 of Fig. 1;

Fig. 3 is a fragmentary sectional view taken along the broken line 3 3 of Fig. 1; and

Figs. 4 to '7 are semidiagrammatic views illustrating successive events in the operating cycle of the fuse valve of the invention.

Referring particularly to Fig. 1 of the drawings, the numeral it designates a fuse valve which embodies the invention, the fuse valve being shown in a hydraulic system which includes a pump I I, a four-way selector valve l2, a double-acting hydraulic unit i3 and a reservoir I4. The inlet of the pump Il is connected to the reservoir I4 by a uid line I5 and the outlet of the pump is connected to the fuse valve IB by a primary inlet or pressure inlet line I6. The fuse valve it is connected to the selector valve I2 by a primary outlet or pressure outlet line l'i, and is also connected thereto by a secondary inlet or return inlet line I 8. The fuse valve Hl is connected to the reservoir I4 by a secondary outlet or return outlet A line I9. The hydraulic unit i3 comprises a cylinder 20 having a piston 2| therein, the ends of the cylinder 20 being connected to the selector valve I2 by fluid lines 22 and 23. As will be discussed in more detail hereinafter, the fuse valve I3 controls iiuid flow through the lines il and I8, the selector valve I2, the lines 221 and 23, and the hydraulic unit I3.

The selector valve I2 is movable from an inoperative or closed position to either one of a pair l of operative or open positions, there being no flow through the system when the selector valve is closed, assuming the lines and i8 are intact. When the selector valve l2 is in either of its open positions, and assuming that the lines El, I8, 22

tion of the arrows 26 to move the piston 2| to the right as viewed in Fig. l of the drawings.

Considering the fuse valve Ill in more detail with particular reference to Figs. 1 and 2 of the drawings, it includes a housing or housing means 3| provided with bosses 32, 33, 34 and 35, the boss 32 being provided with a primary inlet or pressure inlet port 35 which may be threaded (not shown) to receive the primary inlet or pressure inlet line I6, the boss 33 being provided with a primary outlet or pressure outlet port 31 which may be threaded to receive the primary outlet or pressure outlet line il, the boss 34 being provided with a secondary inlet or return inlet port 38 which may be threaded to receive the secondary inlet or return inlet line I8, and the boss 35 being provided with a secondary outlet or return outlet port 39 which may be threaded to receive the secondary outlet or return outlet line |9. The housing 3| is provided with a main or primary valve chamber 43 which extends inwardly from one end thereof and is provided with an accumu- 4 lator or accumulating chamber 44 which extends inwardly from the opposite end thereof and which is aligned with the main valve chamber 43 in the particular construction illustrated. The main valve chamber and the accumulating chamber are interconnected by a bore 45 and a counterbore 46. The housing 3| is also provided with a bore therethrough which provides a secondary valve chamber 48. The outer end of the primary valve chamber l43 and one end of the bore forming the secondary valve chamber d8 are closed by a cover plate 49 which is secured to the housing 3| by screws 50, or the like. Similarly, the outer end of the accumulating chamber 4d and the other end of the bore forming the secondary valve chamber 48 are closed by a cover plate 5| which is secured to the housing 3| by screws 52, or the like.

Reciprocable in the primary valve chamber 43 is a main or primary valve 55 of the pcppet type, the primary valve 55 being adapted to engage an annular seat 56 which is disposed in the primary valve chamber and which abuts a shoulder at the junction of the primary valve chamber with the bore 45. The annular seat 56 carries an annular sealing element, exemplified as an O-ring 5l, for preventing leakage past the outer periphery thereof. The primary valve 55 is biased toward a closed position wherein it engages the annular seat 5S by a spring 58 which is seated against a cup-shaped element 59 disposed in the primary valve chamber 43. The element 59 carries spaced O-rings E0 for preventing leakage past the outer periphery thereof.

The pressure inlet port communicates with the primary valve chamber 43 adjacent the annular seat 56 and the pressure outlet port 31 communicates with the counterbore 46 so that fluid delivered to the pressure inlet port by the pump II may flow through the primary valve chamber 43, the annular seat 56, the bore and the counterbore 46 into the pressure outlet port when the primary valve is disengaged from the annular seat. The primary valve chamber 43, the annular seat 56, the bore A5 and the counterbore 4S will hereinafter be regarded as collectively orming a main or primary passage 6| which connects the pressure inlet and outlet ports 35 and 3l' and which is adapted to be closed by the primary valve 55.

Disposed in the accumulating chamber 44 is a fluid separating means, exemplified as a piston 54, which is adapted to displace fluid from the accumulating chamber through the counterbore 46 into the pressure outlet port 37 as will be discussed in more detail hereinafter. The displace ment piston 64 is biased toward the left, as viewed in the drawings, by a spring 65 which is seated against a sleeve abutting the shoulder formed at the junction of the bore l5 with the counterbore 4S. Movement of the piston 64 under the iniiuence of the spring 65 is limited by an element B which carries an 0-ring 6'!k for preventing leakage past the outer periphery thereof. The displacement piston '54 is beveled at 68 to provide an annular space 69 between the piston and the element 63 when the piston is in the position shown in Fig. 4 of the drawings.

As best shown in Figs. 4 to '7 of the drawings, formed in the housing 3| adjacent the accumulating chamber 44 is a passage 1I which communicates Vwith the. pressure inlet port 35, with the annular space 69 in the accumulating chamber 44 adjacent the element 65 through an oriiice or passage 14, and with the accumulating chamber adjacent the primary valve chamber 43 through fan auxiliary or metering orifice or passage 16, the effective cross sectional area of the passage 14 being controlled by a valve 16, shown in Fig. 3 of the drawings, in a bore' 11 in the housing 3|. The passage 1| also communicates with the accumulating chamber 44 at a point intermediate the passages 14 and 15 through a passage 18, flow into the accumulating chamber from the passage 1I through the passage 18 being prevented by a spring-biased check valve 19.

As will be discussed in more detail hereinafter, uid under pressure may flow from the pressure inlet port 36 through the passages 1I and 14 into the space 69 between the element 66 and the displacement piston 64 to move the latter to the right, as viewed in the drawings, thereby displacing fluid from the accumulating chamber 44 into the pressure outlet port 31. The metering passage 15 is, in eiect, in parallel with the primary passage 6I and permits limited flow of fluid from the pressure inlet port to the pressure outlet port 31 around the primary valve 55, as will be discussed in more detail hereinafter. The displacement piston G4 is adapted to prevent flow from the pressure inlet port 36 to the pressure outlet port 31 by way of the metering passage 15 as it moves from left to right in the accumulating chamber 44, as viewed in Figs. 5 and 6 of the drawings. Thus, the displacement piston 64 also serves as a valve means for terminating flow from the pressure inlet port 35 to the pressure outlet port 31 by way of the metering passage 15.

Referring again to Fig. 2 of the drawings, the return inlet and outlet ports 38 and 39 communicate with the secondary valve chamber 48 at a pair of spaced points, and reciprocablc in the secondary valve chamber is a secondary valve 35 of the piston type. The secondary valve 85 is biased toward a closed position by a spring 86 and, when it is in its closed position, it engages an annular sealing element, exemplified as an 0ring 81, which is carried by an element 88 disposed in the bore forming the secondary valve chamber 48 and seated against a snap ring 89 therein. The element 88 is provided with an annular groove 90 which registers with the return inlet port 38 and which communicates with an axial bore 9| in the element 83 through radial openings 92 therein. The annular groove 90, the radial openings 92, the bore 9| and the secondary valve chamber 48 may be regarded as providing a secondary passage, indicated generally by the numeral 95, which connects the return inlet and outlet ports 38 and 39. As will be apparent from Figs. 2, 4 and 5 of the drawings, the O-ring 91 is disposed between the return inlet and outlet ports 33 and 39 so that the secondary valve 85, when in its closed position wherein it engages. the O-ring 81, closes the secondary passage 95 between the return inlet and outlet ports. As shown in Figs. 6 and '7, when the secondary valve 85 is in its open position, it opens the secondary passage 95.

As viewed in the drawings, the left side of the secondary Valve 85 is exposed to fluid pressure in the return outlet port 39 and the right side thereof. is exposed to fluid pressure in the return inlet port 38 so that the secondary valve will be moved to an open position to open the secondary passage 95 whenever the fluid pressure in the return inlet port exceeds that in the return outlet. port by an amount suilicient to overcome the net spring force applied to the secondary valve 95. Preferably, this net spring force,` which -is produced by the spring 86 and a spring |09 to be discussed later, is sufficient to prevent opening of the secondary valve 85 if the fluid pressure in the let port 3S at all times.

return inlet port 38 is only slightly higher than that in the return outlet port 39, which would be the case if the return inlet line I8 connected to the return inlet port were damaged suiciently to permit excessive loss of fluid therefrom.

In addition to being movable to an open position by a predetermined pressure differential thereacross in the foregoing manner, the secondary valve may be moved to an open position manually by a lever 96 pivotally connected at 91 to a bracket 98 which is clamped between the coverplate 49 and a nut 99. 'Ihe latter is threaded on a stem of an element |0| which is disposed in the bore forming the secondary valve chamber 49 and which carries an O-ring |02 to prevent leakage therepast. the stem |00 extending through openings in the coverplate 49 and the bracket 93. Slidably disposed in a bore |05 through the element |ilI is the head |06 of a plunger |91 having a stem |08 which is adapted to engage and open the secondary valve 85 during movement of the plunger toward the left, as viewed in the drawings. The lever 96 is adapted to engage the head |06 of the plunger |01 to produce such movement of the plunger. The plunger |01 is biased into engagement with the secondary valve 'S5 by the aforementioned spring |09, which is seated against the element IM and against an integral collar |I0 on the plunger |91. It will be noted that the plunger spring |09 opposes the secondary valve spring 8S and, in order to prevent opening of the secondary valve by the plunger spring |09, the spring force applied to the secondary valve by the plunger spring is made smaller than that applied to the secondary valve by the secondary valve spring. As previously indicated, the net spring force applied to the secondary valve 85 is preferably suioient to prevent opening of the secondary valve if' the fluid pressure in the return inlet port 38 is only slightly higher than that in the return outlet port 39.

It will bev noted that the head |96 of the plunger |91 carries an 0-ring i4 to prevent leakage past the plunger head through the bore |05 in the element |0l. It will also be noted that the stem |08 of the plunger |01 carries an integral collar H5 which is slidable in a bore I|6 through an element I |1 which is disposed intermediate the element 88 and l0! and seated against the snap ring 89, the collar H5 carrying an O-ring IIS to prevent leakage therepast. The element I|1 carries a pair of spaced O-rings |I9 to prevent leakage therepast. The function of the element I|1 will be discussed in more detail hereinafter.

The collar H0 on the plunger |91 is disposed in a space |22 between the elements ||l| and Ill and is provided with a tapered surface which is adapted to seat against a complementary surface at one end of the bore IIS in the element l I1 to close this bore. Thus, the collar I I0 serves asa valve and will be referred to as such hereinafter. The housing 3| is provided with a passage |Z3 which corrnnunicatesl at one end with the space |22 and at its other end with the primary valve chamber -43 at a point adjacent the annular seat 50 for the primary valve 55, the

. latter being provided with a portion |24 of reducedA diameter around which fluid may flow from the pressure inlet port i5 into vthe passage |23. Thus, the space |22 between the elements |0I and I |1A communicates with the pressure in- When the valve I|0 is open, fluid' from the space |22 may flow through the bore ||6 in the element ||1 into radial openings in this element, and thence into an annular groove |26 therein, the annular groove being disposed between the O-rings carried by the element ||1 so that leakage from the groove is prevented. The housing 3| is provided with a passage |29 which communicates at one end with the annular groove |26 in the element ||1 and which communicates at its other end with an annular groove |30 in the element 59 in the primary valve chamber 43, the annular groove |30 being disposed between the O-rings carried by the element 59 so as to prevent leakage from this groove. The annular groove |30 communicates with the primary valve chamber 43 through radial openings |3| in the element 59.

It will be apparent that when the secondary valve 85 is closed, the valve I |10 is open so that the uid pressure obtaining in the pressure inlet port 36 is communicated to the space between the element 59 and the primary valve 55 vby way of the annular space around the reduced diameter portion |24 of the primary valve, the passage |23 in the housing 3|, the space |22 between the elements 0| and ||1, the valve ||0, 1

the bore i I6 in the element ||1, the radial openings |25 in the element ||1, the annular groove |26 in the element 1, the passage |29 in the housing 3|, the annular groove |30 in the element 59 and the radial openings |3| in the element 59. Thus, the iiuid pressure obtaining in the pressure inlet port 36 is applied to the right side of the primary valve 55, as viewed in the drawings, thereby biasing the primary valve toward its closed position i. e., biasing the primary valve into engagement with its annular seat 55. However, when the secondary valve 85 is in its open position, the plunger spring |09 closes the valve ||0 carried by the plunger |01 to prevent application of the fluid pressure obtaining in the pressure inlet port 36 to the right side of the primary valve 55. Also, when the secondary valve is in its open position, the space between the primary valve and the element 59 is vented to the return outlet port 39 to permit the primary valve 55 to move to its open position, as will be described in the following paragraphs.

The housing 3| is provided with a passage |34 which communicates at one end with the annular groove |26 in the element I |1 and at its other end with a valve chamber |35 which is provided by a portion of the bore forming the secondary valve chamber 48, the valve chamber |35 being separated from the secondary valve chamber 48 by an annular element |36 which is retained by snap rings |51 and which carries an O-ring |38 to prevent leakage therepast. The element |36 provides a seat for a valve |4| which is, disposed in the valve chamber |35 and which is provided with an integral collar |42 in sliding relation with the peripheral wall of the valve chamber |35. The valve |4| is also provided with a stem |43 which is slidable in a bore |44 in an element |45 in the valve chamber |35, the valve stem |43 carrying an O-ring |45 and the element |45 carrying an O-ring |41 to prevent leakage therepast. The valve |4| is biased toward a closed position wherein it engages the element or seat |36 by a spring |48 which is seated at one end against the collar |42 on the valve |4| and at its other end against the element |45.

It will be noted that when the valve |4| is in its closed position, it prevents fluid flow between the valve chamber |35 and the secondary valve chamber 4 8. However, when the valve |4| is open, fluid may flow from the valve chamber |35 into the secondary valve chamber 48 by way of one or more openings |49 in the collar |42 on the valve |4|.

It will be noted that the secondary valve is provided with a stem |52 thereon which is adapted to engage the valve |4| to open it when the secondary valve is opened. It will also be noted that the valve |4| serves as a seat for the spring 86 which biases the secondary valve 85 toward its closed position, it being necessary for the spring force of the spring 86 to be less than that of the spring |48 to prevent the spring 86 from holding the valve |4| open when the secondary valve B5 is closed.

Considering the function of the valve |4|, it will be recalled that opening of the secondary valve 85 by ud pressure in the return inlet port 38, or manually by the lever 96, results in closing of the valve ||0 carried by the plunger |01 to cut ofl` uid communication between the pressure inlet port 36 and the space between the primary valve 55 and the element 59. As shown in Figs. 6 and 7, opening of the secondary valve 95 also results in opening of the valve |4| so that the space between the primary valve 55 and the element 59 is vented to the return outlet port 39 by way of the radial openings |3| in the element 59, the annular groove |39 in the element 59, the passage |23 in the housing 3|, the annular groove |26 in the element ||1, the passage |34 in the housing 3|, the valve chamber |35, the opening |49 through the collar |42 in the valve |4|, the annular seat element |36 and the secondary valve chamber 48. This permits the primary valve 55 to open, as will be discussed in more detail in the following paragraphs.

As a matter of convenience in discussing the operation of the fuse valve l0, the various passages, grooves, etc., through which the fluid pressure obtaining in the pressure inlet port 36 is communicated to the space between the element 59 and the primary valve -55 under the control of the valve H0 are hereinafter regarded, in Figs. 4 to 7, as collectively forming a pressure passage |55. Similarly, the various passages, grooves, etc., for venting the space between the element 59 and the primary valve 55 to the pressure obtaining in the return outlet port 39 under the control of the valve |4| are hereinafter regarded, in Figs. 4 to '7, as collectively forming a vent pasage |56.

Considering the operation of the fuse valve I0 with particular reference to Figs. 1 and 4 to 'l of the drawings, it will be assumed that the selector valve |2 is in its closed position and that the various fluid lines connecting the fuse valve, the selector valve and the hydraulic unit I3 are intact. Under such conditions the various components of the fuse valve assume the positions shown in Fig. 4 of the drawings.

Referring to Fig. 4 of the drawings, since the selector valve l2 is closed, the duid pressures obtaining in the return inlet and outlet ports 38 and 39 are equal so that the secondary valve 85 closes the secondary passage under the iniuence of the spring force differential applied thereto by the springs 86 and |09, assuming that the lever 96 is in its inoperative position. Since the secondary valve 85 is closed, the valve ||0 opens the pressure passage |55 and the valve |4| closes the vent passage |56. Since the pressure passage |55 is open, the pressure obtaining in the pressure inlet port 36- is applied to the entire right side of the primary value 55, as viewedin the drawings. 'Substantially' the entire left side of the primary valve 55, as viewed in the drawings, is also exposed to the ui'd pressure obtaining in the inlet port .35, the reduced-diameter portion |24 of the primary valve being exposed to such iiud pressure through the passage 1| and the metering passage 15. Thus, under such conditions, the primary valve 55 is balanced, except for the area thereof in contact with the armular seat 56, and is held closed by the spring' 5S. Since the selector valve is closed, no fluid can now from the pressure inlet port 35 into the pressure outlet port 31 through the metering passage 15 in parallel with the primary passage so that the pressure obtaining in the pressure inlet passage is applied to the right side of the displacement piston 6a, as viewed in the drawings. The same pressure is applied to the left side of the displacement piston through the passage 1d so that the displacement piston is balanced under the conditions being considered vand is maintained in the position shown in Eig. 4 of the drawings by the spring o5.

Referring now to Fig. 5 of the drawings, it will be assumed that the selector valve I2 has been moved to one of its open positions so as to admit fluid to one end of the cylinder 23. As soon as the selector valve l2 is opened, the pressure in the pressure outlet port 31 decreases so as to produce across the displacement piston Se' a pressure diierential which moves the displacement piston to the right, as viewed in the drawings, against the action of the spring E5. The conditions under consideration are illustrated in Fig. 5 of the drawings wherein .the displacement piston Ell is shown in an intermediate position. Such movement of .the displacement piston se displaoes huid into .the pressure outlet line i1 connected to the pressurev outlet port 3?, and additional fluid is meteredinto .the pressure outlet line through the metering passage 15.

lf the I'iuid lines .|1, `|8, `22'and -23 are intact, the fluid introduced into the line I1 in' vthe foregoing manner displaces the piston 2| in its cylinder 2G, whereupon the piston di'splaces uuid from the cylinder into the lines 22 and I8, thereby producing a return'ow of fluid to the use valve |3. However, if' any of .the lines I1, I8, 22 and 23 is broken, .or .is damaged to such an extent that lluid is lost at. an excessive rate, no return now to the fuse valve will be established, or the return flow will be insufcient to produce in the return inlet port. 38. a fluid pressure sumcient to effect the remaining events in the operating cycle Aof the fuse' valve. Irrespective of whether the connections between the pressure outlet port y31 and `return inlet port .38 are intact or damaged, the displacement piston .Sd will vclose the auxiliary metering passage as -it approaches the position shown in Fig. 6 or the drawings so that only .alimited amount of uuid is displaced and meteredgintoethe pressurey outlet line l1- Thus. if no .return dow .through the Yfuse val-ve I0 is establishedbecause of the. existence of broken or damaged lines, o ryother parts, ,which permit excessive loss. of fluid, only a limited amount 0f fluid will be isst-from thesystem, such limited amount heise .equal to Athe sum .of the amount displaod by .the PsiiOIl 3 4 and ,the

amount metered by the metering passage 1.5. The metering action w 1 he ,discussed in ,more detail .ur-0n emulation mme `dissi.sion vor .the remaining errate' is manners/.tios .cycle .of vthe fuse-ral@ .Ll

Assuming now that the connections between the pressure outlet port 31 and the return inlet port 38 are intact so that a return now is established by the piston 2| of the hydraulic unit I3, the pressure in the return inlet port l3 3 will exceed that in the return outlet port 313. Thus, a pressure diferential for moving the secondary valve 35 from its closed position to its open position is impressed on the secondary valve, the secondary valve being shown open in 6 of the drawings. As the secondary valve 35 is opened in the foregoing manner, the valve I I0 closes the pressure passage 55 and the valve I4! opens the vent passage |56 so that the pressure applied to the right side of the primary valve 55, as viewed in the drawings, is reduced to the pressure obtaining in the return outlet port 39. Thus, the valve iid and idi impress on the primary valve a pressure differential for moving the primary valve from its closed position to its open position, the primary valve being shown in its open position in Fig. 7 of the drawings. Thus, the primary valve 55 permits fluid for operating the hydraulic unit I3 to now from the pressure inlet port 36 directly to the pressure outlet port 3l through the primary passage 6I.

As the primary valve 55 opens, the pressures applied to opposite sides of the displacement piston ed are equalized so that the spring 65 returns the displacement piston to its initial po`- sition. Return of the displacement piston d'to its initial position is facilitated byv opening of the check valve i9 controlling now through the passage i8.

Thus, if the connections between the pressure outlet port 31 and the return inlet port 38 are intact, the various components of the fuse valve ill assume the positions shown in Fig. 7 of the drawings upon opening of the selector valve I2'. However, if the connections between the ports 31 and 38 are not intact, the various components of the fuse valve will assume the positions shown in Fig. 5 of the drawings, except that the displacement piston will be at the end of its travel so as to close the metering passage'l. Consequently, ii broken or damaged lines are encountered, the loss of uid will be equal' only to that displaced by the piston 64 and metered through the passage 15.

The fuse valve I0 may also be operated manually by rotating the lever It into the position shown in Figs. 6 and 7 of the drawings, thus opening the secondary valve through the plunger |61. Opening of the secondary valve 85 causes the valve lid to close the pressure pas"- sage |55 and the valve Ill! to open the ventpa's'- sage |55 with the result that a pressure differential is applied to the primary valve 35 to move it to its open position. It will be understood that the fuse valve it will normally be operated"auto-- matically, but that manual operation thereof may be desirable or necessary in some instances. For example, in the event that a damaged connection between the pressure outlet port 31 and thereturn inlet port 33 has been repaired, manual operation of the fuse valve I@ may .be .desirable to facilitate relling the lines with fluid. Also, manual operation of the fuse valve Iii Ymay be necessary in an emergency to permit Iactuation of some component of an airplane if 4the fluid lines leading to the hydraulic unit I3 are intact, even though one of the lines leading from the hydraulic unit may be broken. Manual operation vof the fuse valve under such circumstances 64 at a relatively high rate.

- ing time.

11 will entail loss of fluid from the system, but such loss may not be objectionable in an emergency. An important feature of the present invention `is that the total quantity of fluid displaced by the piston 64 and metered by the orice or passage 15 is substantially independent of the vscosity of the fluid and is thus substantially independent of temperature so that the fuse valve Vwill operate in substantially the same manner in extremely cold and extremely hot climates. It will be apparent that if the viscosity of the fluid is low, fluid will be metered through the passage 'l5 at a relatively high rate, and will ow through the passage '54 into the space E9 at a relatively high rate to displace the piston Similarly, if the viscosity of the fluid is high, the metering rate will be low and the displacement rate Will be low. Thus, when the viscosity is low, the high displacement rate reduces the length of time that metering at a high rate occurs, and, when the Viscosity is high, the low displacement rate increases the length of time that metering at a low rate occurs.

Thus, by employing a high displacement rate to reduce the time of metering at a high rate and a low displacement rate to increase the time of metering at a low rate, the quantity of fluid metered, and thus the total quantity of fluid metered and displaced, are maintained substantially constant despite viscosity variations arising from temperature variations, or from other causes.

In addition to being capable of delivering to the hydraulic unit |3 a fluid sample which is substantially constant with viscosity variations, the fuse valve I!) is capable of delivering thereto a fluid sample of much larger volume than the volume of displaced fluid because of the combined metering and displacement action. If desired, the volume of displaced iiuid may be small compared to the Volume of iiuid necessary to establish return now, the remainder of the fluid necessary to establish return flow being metered through the orice or passage '15. Consequently, the accumulating chamber M may be quite small, thereby minimizing the size and weight of the fuse valve, which is an important feature of the invention. Thus, the present invention provides a fuse valve having the advantages of prior fuse valves operating on the displacement principle without the use of a large accumulating chamber.

Another feature of the present invention resides in the fact that the volume of the fluid sample may be increased or decreased readily in accordance with the requirements of different installations by the simple expedient of adjusting the valve 'I6 to vary the effective area of the passage T4, thereby varying the displacement rate of the piston 64 and thus varying the meter- Thus, the fuse valve I!! may be incorporated in installations requiring fluid samples of different volume.

Another important advantage of the fuse valve I over prior fuse valves is that extremely small forces are required for manual operation. It will be noted that, in operating the fuse valve l0 manually, it is necessary to apply to the lever 96 a force su'icient only to overcome frictional resistance to movement of the plunger |01, the secondary valve 85 and the valve |4|, to overcome the net spring force of the springs 36, and |48, and to overcome any slight pressure differential applied to the plunger ill'i, the pressure applied to the plunger being small for an in# stallation wherein the pressure in the reservoir I4 is equal to atmospheric. Since the primary valve 55 is actuated by the pressure differential impressed thereon by the valves Ill) and |4|, it is unnecessary to oppose the pressure acting on the primary valve when operating the fuse valve l0 manually in the foregoing manner, which is not true of prior fuse valves of which I am aware.

Still another feature of the present invention is that, with the exception of the O-ring H4 on the plunger head |06, the O-ring H8 on the plunger collar H5 and the O-ring |46 on the valve stem |43, no seals are employed between relatively moving parts, thereby substantially eliminating seal wear and appreciably extending the service life of the valve. The foregoing is accomplished without appreciable fluid leakage, which is another feature. For example, fluid leakage past the primary valve 55 is prevented by engagement thereof with the annular seat 56 when the primary valve is closed, and liuid leakage past the primary valve is prevented by engagement thereof with a seat |51 on the element 59 when the primary valve is open. Similarly, when the displacement piston 64 is at the end of its stroke, leakage therepast is prevented by engagement of the displacement piston with a seat |58 formed by the shoulder at the junction of the accumulating chamber :i4 with the counterbore 46, there being no tendency toward leakage past the displacement piston when it is in the position shown in Fig. 4 of the drawings since the same pressure obtains on both sides thereof. When the secondary valve is closed, fluid leakage therepast is prevented by the O-ring 94 and, when the secondary valve is open, it registers with the return outlet port 39 so that the same pressure obtains on both sides thereof. Leakage of fluid from the valve chamber |35 into the secondary valve chamber 48 is prevented by the valve 14|. Thus, leakage is substantially eliminated without the use of seals between relatively moving parts.

Although the fuse valve |0 has been described in connection with a hydraulic system which is normally closed, as by the selector valve l2, it will be understood that it may be used in a normally open system, in which case it is normally open and closes in the, event of a line break. Also, one fuse valve I0 may be used in connection with several selector valves, either in parallel in a closed system, cr in series in an open system.

Although I have disclosed an exemplary embodiment of my invention herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in the embodiment disclosed without departing from the spirit of the invention.

I claim as my invention:

1. In a valve device, the combination of: a main passage; normally closed main valve means for controlling flow of fluid through said main passage; an auxiliary, metering passage in parallel with said main passage; an accumulator; fluid separating means movable in said accumulator between two positions, said auxiliary passage bypassing said fluid separating means in at least one of said positions of said uid separating means; a passage providing fluid communication between said main passage upstream from said main valve means and said accumulator on one side of said uid separating means;

a passage ,providing fluid communication :between sa-id main passage downstream from .said valve means and .said accumulator on the opposite iside lof said viiuid separating means, said fluid separating means `displacing duid into the passage .last defined 'du-ring .movement thereof `from said one position vtoward the 'other 'ci said positions; and means for openingsaidmain valve means.

2. A valve device as set forth in claim l including auxiliary valve means carried by :said -iuid separating .means :for yclosing said `auxiliary passage 'after a predetermined movement fof .said iiui'd separating means from said one position.

'3. In a valve device, .the combination of housing means having a primary iinlet port, :a ,pri-mary outlet port, a vsecondary iniet port, ia :secondary outlet port, a primary passage connecting said primary inlet 'and outlet ports, Tlan :auxiliary metering passage connecting said primary inlet and outlet ports, :a `chamber 'communicating at one end with said primary .inlet :port yand :at .its other end with said primary 'outlet port, and a secondary .passage `connecting sai-d :secondary inlet 'and outlet ports; :normally closed .primary valve means for Icontrolling .flow of .fluid through said primary passage and adapted 'to ;be 'opened in response to flow tof iiuid `through said fsecondary passage; fand fiuid 'separating :means movable in'said 'chamber ifrom-'said'one end thereof -toward 'said other end thereof to Vdisplace iiuid from `said chamber .into said :primary 'outlet port, said auxiliary .passage vv.bypassing lsaid iiuid sepa- Jrating means when said iuid :separating means :is 'at said one endof saidfchamber.

.4. A `valve dev-ice fas set .forth .fin .claim .3 :in- :cluding Aauxiliary valve means .carried by :said fluid separating means for automatically fclosing said auxiliary passage after :a predetermined movement of .said fluid :separating means from said one end of said chamber.

5. `A valvedeviceas Asetl forthin vclaim'l3wherein said primary valve means is adapted .to be opened by a iiuid pressure diiferential impressed thereacross, said valve device including means operable in response to Yflow of fluid through said 'secondary passage *for impressing said iiuid pressure differentialacrosssaidprimary valve-means.

"6. Avalvedeviceassetforth'in claim 43 wherein said primary valve means is adapted to be opened by a fluid pressure differential impressed thereacross, said valve device including means responsive to a iiuid pressure difference between said secondary inlet and outlet ports for impressing said fluid pressure differential across said primary valve means.

7. In a valve device, the combination of housing means providing a primary inlet port, a primary outlet port, a secondary inlet port, a secondary outlet port, a primary passage connecting said primary inlet and and outlet ports, and a secondary passage connecting said secondary inlet and outlet ports; normally closed primary valve means for controlling flow of fluid through said primary passage and movable to an open position by a fluid pressure differential impressed thereacross; means for discharging .a predetermined quantity of fluid into said primary outlet port; and means mechanically unconnected to said primary valve means and responsive to a fluid pressure diiference between said secondary inlet and outlet ports for impressing said fluid pressure diiferential across said primary valve means.

8. A valve device as set forth in claim 'I wherein 14 the means last :defined includes normally closed secondary valve means for controlli-trg idaW @i fluid through said secondary passage and able to van A.open position in -response'to said iiuid pressure difference.

9. A valve device as `set forth .in claim 7 .including manually operable means for actuating .the means last defined :in claim .1.0. Y

10. In a valve device, the .combination of.: housing means having .an .inlet jport., an outlet port and -a passage connecting .said iper-13.5,; .mirmally closed valve means for .controlling flow vof ii-uid through said vpassage .and .moyable .to -an Iopen yposition .in .response to a fluid ypressure .differential impressed thereacross;; and .manually .operable means mechanically .unconnected .to said valve means .for impressing ...said fluid .pressure differential .across said valve `means.

11. In a valve device, .the 1combination of; housing means having a primary Ainl-et port. .a .primary outlet port, .a .secondary inlet port, .a secondary outlet eport, a primary passage con.-

-necting said primary ninlet :and :outlet smiths, .a

secondary .passage ,connecting .Said .secondary inlet and -outlet,ports,..a F.primary valvechamher, .a pressure passage connecting -said .primary `.inlet port and .said l.primary ivalve chamber.. .and a vent passage connecting .said primary .valve chamber and said :secondary loutlet port; l.pri-- .mary valve means exposed to iiuid pressure .in said primary valve chamber forfclosing-said pri.- mary passage; no-rmallyopen ythird valve means .for controlling fiow of .fluid through saidmrssure passage; normally closed .fourth valve means for controlling new pf iuid .through ...Said vent passage; actuating .means :for .closing .said third valve means and forbpeningsaid fourth valve lmeans so as to rpreventdiuid.communication between said Vvprimary .inlet port ...and -said primary valve chamberanditoaprovide uid com.- munication .between said .primary `.valve...chamber .and said secondary .outlet port; .and means .for

delivering Ia quantity `.of .fluid to .said r.primary outlet port .independently .of the l.position of 1.said

fprimary valve means.

-ally ,operable .meansior closinasaid third .valve meansfand opening said fourthvalvemeans.

13. A valve device as set 'forth ineclam ,-Jrl wherein said actuating means includes means movable in response to a fluid pressure difference between said secondary inlet and outlet ports for closing said third and opening said fourth valve means.

14. A valve device as set forth in claim 13 wherein the means defined in claim 13 comprises normally closed secondary valve means for controlling fluid flow through said secondary passage.

15. In a valve device, the combination of a main passage; normally closed main valve means for controlling flow of fluid through said main passage and movable to an open position by a fluid pressure differential impressed thereacross; a chamber; a passage connecting one end of said chamber to said main passage upstream from said main valve means; a passage connecting the other end of said chamber to said main passage downstream from said main valve means; an auxiliary, metering passage communicating with said main passage upstream from said main valve means and communicating with said chamber intermediate its ends; uid separating means movable 1n said chamber from said one end.

thereof toward said other end thereof for displacing fluid from said chamber into said main passage downstream from said main valve means vand for terminating flow of fluid from said auxiliary metering passage into said main passage downstream from said main valve means as it approaches said other end of said chamber; and means for impressing said iiuid pressure differential across said main valve means.

16. In a valve device, the combination of: housing means having a primary inlet port, a primary outlet port, a secondary inlet port, a sec- -ondary outlet port, a primary passage connecting :said primary inlet and outlet ports, a secondary passage connecting said secondary inlet and outlet ports, an accumulating chamber communieating at one end with said primary inlet port and at the other end with said primary outlet port, an auxiliary, restricted, metering passage connecting said primary inlet and outlet ports, a primary valve chamber, a pressure passage connecting said primary inlet port and said primary valve chamber, and a vent passage connecting said primary valve chamber and said secondary -outlet port; a primary valve exposed to ilud pressure in said primary valve chamber, said primary valve being adapted to control flow of fluid through said primary passage and being biasable toward a closed position by fluid pressure in said primary valve chamber; a secondary piston valve for controlling flow of uid through said secondary passage, said secondary piston valve having areas respectively exposed to fluid pressures in said secondary inlet and outlet ports and being biasable toward an open position by a fluid pressure difference between said secondary inlet and outlet ports; a normally open third valve for controlling'flow of iuid through said pressure passage; a normally closed fourth valve for controlling iiow of fluid through said vent passage; means operable in response to movement of said secondary piston valve toward an open position for closing said third valve and opening said fourth valve; a piston movable in said accumulating chamber from said one end thereof toward said other end thereof; and means on said piston for closing said restricted metering passage during movement of said piston from said one end of said accumulating chamber toward said other end thereof.

17. In a valve device, the combination of: a housing; a primary passage formed in said housing; a normally closed primary valve in said housing and controlling fluid iiow through said primary passage; a metering passage formed in said housing in parallel with said primary passage and by-passing said primary valve for discharging fluid into said primary passage downstream from said primary valve; a chamber formed in said housing; displaceable uid separating means in said chamber and communieating on one side with said primary passage upstream from said primary valve and communieating on its other side with said primary passage downstream from said primary valve for discharging fluid into said primary passage downstream from said primary valve, said fluid separating means being movable between two positions and said metering passage bypassing said fluid separating means in at least one of said positions of said iiuid separating means; a secondary passage formed in said housing and connectible in series with said primary passage on the downstream side of the primary valve; and means in said housing and operable by a ow of iiuid through said secondary passage for opening said primary valve.

18. A valve device according to claim 1'7 wherein said primary valve is adapted to be opened by a fluid pressure differential impressed thereacross, the means last dened in claim 17 including movable means in said secondary passage and responsive to a diierence in uid pressure between the upstream and downstream ends of said secondary passage, and the means last defined in claim 17 further including valve means connected to and operable by said movable means for impressing said uid pressure differential across said primary valve.

PHILIP L. REYNOLDS.

References cited in the me of this patent UNITED STATES PATENTS Number Name Date 2,428,150 Field Sept. 30, 1947 2,478,210 Sprague Aug. 9, 1949 2,478,211 Sprague Aug. 9, 1949 2,493,906 Wishart Jan. 10, 1950 

